For the OneBusAway iPhone app to be able to access your current location to show you nearby bus stops, location services need to be enabled for the app.  Location services can sometimes be accidentally disabled when you upgrade your phone or reinstall an app.  Here's a quick guide to make sure the service is enabled.

1. From your phone's home screen, select the Settings app.
2. Select the "General" settings item.
3. Select "Location Services"
4. Make sure location services are enabled for the OneBusAway app.

See the pictures below for a step-by-step walk-through.